Forty suspected illegal aliens crammed inside a filthy rental truck apparently were on their way to Delaware when the truck crashed into a car Wednesday night at a Bay Bridge toll plaza, authorities said yesterday.

Immigration officials were questioning the driver of the Ryder truck and its occupants yesterday, but no federal charges had been filed.

"This operation certainly fits the profile of a commercial smuggling operation," said Stephen Fickett, deputy district director for the Immigration and Naturalization Service. "Whether it will prove to be, I can't speculate."

The passengers were discovered after the collision on the west side of the Bay Bridge plaza at 8:40 p.m. The truck rear-ended a Toyota Celica as it approached the plaza, causing minor injuries to two passengers in the truck and to the driver of the car, said spokesmen from the INS and the Maryland Transportation Authority.

The truck's occupants, 21 Guatemalan and 19 Mexican nationals, were detained by the INS pending further investigation. It is the largest suspected alien smuggling case in Maryland since the arrests of more than 60 Chinese nationals in Prince George's County in 1994.

INS officials said the truck was rented in Phoenix, Ariz., on Monday, and conditions inside it were squalid.

Containers of human waste were found in the truck, investigators said. Many of the passengers were ill-dressed for the cold weather clad in lightweight jackets and other clothing.

"They had probably been traveling continuously [since Monday]," Mr. Fickett said. "We tried to take care of them as best we can. We fed them a nice breakfast this morning and lunch."

He said it is unclear when or where the passengers were picked up, or exactly where they were going. The passengers included three boys and a girl.

The other passengers were men. All were expected to be taken to detention centers in Howard or Wicomico counties after being questioned by INS investigators in Baltimore, he said.

Those not needed as witnesses and those with no criminal record probably will choose voluntary departure and leave the country early next week, Mr. Fickett said.

Hermalindo Velasquez Rivera, 18, the driver of the truck, was charged by transportation authority police with driving without a license and driving a rental vehicle in violation of the rental agreement. He was held yesterday in the Anne Arundel County Detention Center in lieu of $1,200 bail.